1. Field of the Invention
The present invention relates to a method and apparatus for performing active scanning in a wireless local area network (WLAN), and more particularly, to a method and apparatus for performing a fast initial link setup (FILS).
2. Related Art
A wireless local area network (WLAN) technique has recently been evolved roughly in three directions. An effort for further increasing a transfer rate is made as an extension of the evolution of the legacy WLAN, and examples thereof include institute of electrical and electronic engineers (IEEE) 802.11ac and IEEE 802.11ad. The IEEE 802.11ad is a WLAN technique which uses a 60 GHz band. In addition, a broadband WLNA which utilizes a frequency band less than 1 GHz is recently emerged to enable broader band transmission in comparison with the legacy WLAN, and examples thereof include IEEE 802.11af which utilizes a TV white space (TVWS) band and IEEE 802.11ah which utilizes a 900 MHz band. These techniques are primarily aiming at not only a smart grid and a broadband sensor network, but also an extension of an extended range Wi-Fi service. In addition, the legacy WLAN medium access control (MAC) technique has a problem in that an initial link setup time becomes significantly long in some cases. In order to solve such a problem, an IEEE 802.11ai standardization action is actively carried out recently to allow a station (STA) to be able to rapidly access an access point (AP).
The IEEE 802.11ai is a MAC technique which deals with a fast authentication procedure to remarkably reduce an initial set-up and association time of the WLAN, and a standardization action was formally started as a task group on January, 2011. To enable a fast access procedure, there is ongoing discussion carried out in the IEEE 802.11ai for procedure simplification in an area of AP discovery, network discovery, time synchronization function (TSF) synchronization, authentication & association, procedure combination with a higher layer, etc. Among them, there is ongoing discussion actively carried out for ideas such as procedure combination which utilizes piggyback of dynamic host configuration protocol (DHCP), optimization of full extensible authentication protocol (EAP) which uses concurrent IP, effective selective access point (AP) scanning, etc.